He said, "In the past we had multiple teams working on different versions of Windows. Now we have one team with a common architecture. This allows us to scale, create Universal Windows Apps."

Although separate versions of Windows will still exist, the Universal Apps platform first mentioned at the Build Conference in San Francisco earlier this year will mean that all devices, regardless of form factor and screen size, will be able to run the same programs and apps.

He explained, "One of beauties of Universal Windows app is, it aggregates for the first time for us all of our Windows volume.

"The fact that even what is an app that runs with a mouse and keyboard on the desktop can be in the store and you can have the same app run in the touch-first [device] on a mobile-first way gives developers the entire volume of Windows, which is 300 plus million units as opposed to just our [four percent] share of mobile in the US or 10 [percent] in some countries."

The new combined infrastructure will roll out with Windows 9, due next year, also covering Windows Phone, Windows RT and the new Windows with Bing, which Nadella said will arrive in time for Christmas 2014.

Microsoft is presently seeking a route back to dominance of its flagship operating system. Windows 8.x has met with an extremely lacklustre response, which has captured less than 15 percent of the market, compared to its predecessor Windows 7 which continues to grow at over 50 percent.